Mechanisms that enable the lowering and elevation of vehicle axles and in particular, the axle of a trailer, in order to adjust the height of an associated cargo bay from ground level, are well known. It is often a necessity that when loading large or heavy objects onto a trailer that the loading deck of the trailer is lowered to be close to the surface of the road to assist loading.
Typically the lowering and elevation of a trailer is achieved through the use of either hydraulic or electrical motor driven systems and also through manually operated mechanisms. Whilst the use of all of the above may achieve the desired result, hydraulic systems in particular are expensive and when used in relation to relatively low weight loads such as motor cycles, lawnmowers and the like, being over specified and unnecessary. As such, it would be useful in many scenarios to provide an assembly specified appropriately for loading such low weight items, for an affordable price. In particular, it would be advantageous to provide such an assembly that incorporates at least some conventional, readily available parts, such as conventional torsion bar suspension arrangements and conventional swing arms, in order to reduce the need for producing bespoke and potentially expensive parts.
A range of electrically and manually operated solutions to adjust the height of vehicle and in particular, trailer axles, are currently in existence. For example, U.S. Pat. No. 6,592,139 discloses a linkage mechanism to pivot the wheels of a trailer around a raised axis in order to adjust the axle height of the trailer. However, the multiple linkage points and lack of mechanical advantage provided when operating the mechanism are likely to generate large friction forces, which would prove difficult to operate and increase the likelihood of mechanical failure. Furthermore, due to the multiple linkage design, the disclosed invention poses a further drawback by requiring a considerable amount of space under the trailer and would prove cumbersome to retro fit to an existing trailer. Accordingly, it would be beneficial in many instances to provide a reliable, compact and simple solution that can be produced as a discrete assembly, adapted to be fitted to existing conventional trailers.
An alternative solution that attempts to resolve some of these problems is disclosed in U.S. Pat. No. 2,807,381 in which a mechanism that uses a cable and winch arrangement to alter the position of the wheels and accordingly alter the height of the trailer is shown. However there are also a number of drawbacks inherent in this solution, for example, the single winch arrangement dictates that the axle height of each wheel of the trailer are adjusted simultaneously and accordingly, can not be adjusted independently. Also the cables are likely to stretch during use or break.
Accordingly, it would be useful to provide a solution that avoids or substantially alleviates any of the disadvantages present in the prior art, or which provides a useful alternative to the prior art approaches.